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Mechanical properties of LDPE/granular starch composites
Author(s) -
Willett J. L.
Publication year - 1994
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1994.070541112
Subject(s) - materials science , composite material , ultimate tensile strength , composite number , low density polyethylene , elongation , volume fraction , polyethylene , modulus , young's modulus , starch , chemistry , biochemistry
The mechanical properties of composites of granular starch and low density polyethylene (PE) have been studied as functions of starch volume fraction ϕ, granule size, and presence of compatibilizer. Property–volume fraction relationships were interpreted using various theories of composite properties. The dependence of elongation (ϵ ∼ ϕ 1/3 ) and tensile strength (σ ∼ ϕ 2/3 ) agree with theoretical predictions, although the proportionality constants are less negative than theoretical values. The addition of compatibilzer (ethylene‐ co ‐acrylic acid copolymer, EAA) did not significantly affect the elongation or tensile strength, but significantly increased the composite tensile modulus. The cornstarch/PE moduli could be described by the Kerner or Halpin‐Tsai equations. Analysis of the composite moduli data using the Halpin‐Tsai equation allowed the estimation of the modulus of granular starch. The value obtained, 15 GPa, is considerably greater than most unfilled synthetic polymers of commercial importance, but significantly lower than the modulus of cellulose. It is also greater than a previously reported value of 2.7 GPa. © 1994 John Wiley & Sons, Inc.